TY - JOUR
T1 - Delaying breakup and avoiding air entrainment in curtain coating using a two-layer liquid structure
AU - Mohammad Karim, Alireza
AU - Suszynski, Wieslaw J.
AU - Pujari, Saswati
AU - Francis, Lorraine F.
AU - Carvalho, Marcio S.
N1 - Funding Information:
This research was supported by the Dow Chemical Company .
Publisher Copyright:
© 2019 Elsevier Ltd
PY - 2020/2/23
Y1 - 2020/2/23
N2 - Successful curtain coating is limited by two flow instabilities, the breakup of the liquid curtain below a critical flow rate and air entrainment above a maximum substrate speed. These limitations make thin film coating at high speed a great challenge. Previous work has shown that the curtain breakup can be delayed to lower flow rates if the flowing liquid has viscoelastic behavior. However, viscoelastic stresses near the dynamic contact line destabilize the flow in that region, leading to the onset of air entrainment at lower web speeds. We propose and experimentally validate the use of a two-layer curtain coating configuration, with a shear-thinning liquid as the bottom layer and a viscoelastic liquid as the top layer, that expands the processing window and enables thin coating at high speeds.
AB - Successful curtain coating is limited by two flow instabilities, the breakup of the liquid curtain below a critical flow rate and air entrainment above a maximum substrate speed. These limitations make thin film coating at high speed a great challenge. Previous work has shown that the curtain breakup can be delayed to lower flow rates if the flowing liquid has viscoelastic behavior. However, viscoelastic stresses near the dynamic contact line destabilize the flow in that region, leading to the onset of air entrainment at lower web speeds. We propose and experimentally validate the use of a two-layer curtain coating configuration, with a shear-thinning liquid as the bottom layer and a viscoelastic liquid as the top layer, that expands the processing window and enables thin coating at high speeds.
KW - Capillary hydrodynamics
KW - Curtain coating
KW - Liquid sheet breakup
KW - Two-layer coating
KW - Viscoelasticity
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U2 - 10.1016/j.ces.2019.115376
DO - 10.1016/j.ces.2019.115376
M3 - Article
AN - SCOPUS:85075998157
SN - 0009-2509
VL - 213
JO - Chemical Engineering Science
JF - Chemical Engineering Science
M1 - 115376
ER -